Hi Dave,
I found your December 2005 paper on a general sockets API for Lisp at http://www.findinglisp.com/papers/sockets-analysis-0-2-5.pdf. Interesting reading for someone working on exactly that topic.
You're saying there that there's a lot to be desired in Lisp sockets and I agree. Though you also claim that UDP is not feasible in many lisp implementations. I have to disagree there: I'm working on usocket, a minimal sockets portability library. Minimal in the sense that I try to keep the layer between the implementation and the application as thin as possible to prevent as much overhead as possible. When you're interested, you can find my analysis on providing UDP sockets on all supported implementations but LispWorks at http://trac.common-lisp.net/usocket/wiki/DatagramSockets.
I'm currently working on implementing a multiplexing model other than blocking threads (important!). After that I'll proceed to UDP. From there on I'll go the socket options and shutdown route.
I hope you'll follow the usocket project with interest and I'm hoping for any comments you can provide.
bye,
Erik.